U need an
allergy testing to find out the probable allergen. If u r found to be sensitive to many proteins/allergens, u may need a short course of systemic
steroids and then antihistamines for prolonged period of time. If antihistamines found to ineffective, u may need to take a low dose steroid daily.
But, u also need to rule out any infective causes like
scabies, body
lice etc